Back-rest for dental chairs.



No. 644,644. v Patented Mar. 6, I900; a. SIBLEY.

BACK BEST FOR DENTAL CHAIRS.

(Application filed July 28, 1899.)

No Model.)

\(Vitncsses.

Attorney.

TNE "gums P IYERs co, FHOYGL THU, WASHINGTON, u. c.

' UNITED STATES PATENT QFFICE'.

GIDEON SIBLEY, OF PHILADELPHA, PENNSYLVANIA.

BACK-REST FOR DENTAL CHAIRS.

SPECIFICATION forming part of Letters Patent No. 644,644, dated March 6, 1900.

Original application filed February 5, 1897, Serial No. 622,092. Divided and this application filed July 28, 1899. fierial No. 725,342. (No model.)

To all whom it may concern:

Be it known that I, GIDEON SIBLEY, a citizen of the United States, residing in the city and county of Philadelphia, in the State of Pennsylvania, have invented certain new and useful Improvements in Back-Rests for Den tal Chairs, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

The present application is a division of the application filed by me February 5, 1897, Serial No. 622,092, for certain improvements in dental chairs.

The subject of this case relates more especially to the back-rests of dental and other chairs, my object being mainly to provide a simple and efficientconstruction whereby the requisite inclination of the back in respect to the seat frame may be readily attained, as will be hereinafter particularly described and claimed.

In the drawings, Figure 1 is an elevation of a chair embodying my improvements. Fig. 2 is a vertical section through the swinging back-frame of the chair. Fig. 3 is a section, enlarged, as on the line 3 3 of Fig. 2. Fig. 4 is a section as on the line 44. of Fig.3.

75 is the back-frame, which is hingedly connected at its lower end with lateral lugs 76 on the seat-base, so that said frame, with its appurtenances, may be swungbackward and forward, as desired, and 77 77 are two arms which are pivoted to a boss on the back of said base and are extended into the frame, so that if the frame and arms be clamped together the frame will be sustained in the desired position of adjustment.

- as to lie between the inclined walls of the block.

The central roller is slightly larger than the others and is arranged to act against the wall 7 8 only, the opposite wall 7 8 being grooved, as at 78*, in the path of said roller. This roller extends into the groove, and in consequence the outer rollers while bearing against the surfaces of the wall 7 S laterally of the groove are not in contact with the opposite wall 78. It will be seen that by moving the nut backward by means of the screw the rollers will bear upon the opposing inclined walls of the block and force the parts of the latter against the arms in a manner to clamp the several parts together and that, on the other hand, by moving the nut forward the parts will be released so as to permit the requisite inclination of the back in respect to the seat section. If a single roller were employed, it would merely slide against the opposing beveled walls of the clamp-block by reason of the reverse actions of the walls upon the roller; but where a series of independent rollers are used they bear only against their respective Walls, thus efiecting a free rolling contact therewith and facilitating the operation of actuating the block.

It will be obvious that the clamping devices above described may be advantageously used for securing other movable parts in po sitions of adj ustmentand that therefore the invention is not restricted to the particular application thereof hereinbefore specified.

I claim- 1. In a dental chair, the combination with an adjustable. portion, and a clamping member therefor provided with two opposite walls, one of which is inclined, of a series of concentric disk rollers one of which acts against one of said walls and another against the opposite wall, a support for said rollers and means for adjusting said support.

2. In a dental chair, the combination with an adjustable portion, of a clamping member therefor provided with oppositely-inclined jaws or walls, independently-rotatable disk rollers bearing against the respective jaws or walls, a support for said rollers, and means for adjusting said support, whereby the said rollers in their action against the oppositelyinclined jaws or walls will be free to rotate reversely of each other.

3. In a dental chair, the combination, with an adjustable portion, of a clamping member therefor having oppositely-inclined walls one of which is provided with a longitudinal groove, three concentric disk rollers whereof the central roller is slightly larger than the others and is adapted to turn freely within the said groove and to bear upon the opposite wall, while the other rollers bear only upon the grooved Wall in paths laterally of the said groove, a support for said rollers, and means for adjusting said support, substantially as described.

4. In a chair, the combination,with the seat, and the swinging back-frame, of the pivoted supporting-haremendinginto said frame, the clamping-block for said bar provided with an inclined wall, a roller engaging said wall, a support for said roller, and means in the back-frame for adjusting said support, substantially as described.

5. In a ohai r, the combination,with the sea and the swinging back-frame, of the pivoted supporting-bar extendinginto said frame, the clamping-block for said bar provided with an inclined wall, a roller engaging said wall, a nut provided with a support for said roller, and an actuating screw for said nut supported in the back-tram e, substantially as described. v

6. In a chair, the combinatiomwith the seat and the swinging back-frame, of the pivoted supporting-bars extending into said frame, the two-part expansible clamping-block provided with oppositely-inclined walls, independent rollers bearing against the respective walls, a nut provided with a support for said rollers, and an actuating-screw for said nut supported in the back-frame, substantially as described.

, In testimony whereof I have hereunto affixed my signature in the presence of two subscribing witnesses.

GIDEON SIBLEY.

\Vitnesses:

ANDREW V. GROUPE, JOHN R. NOLAN. 

